1. Field of the Invention
The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus which reads an image on an original while moving the original with respect to a reading section.
2. Description of the Related Art
Conventionally, an image reading apparatus used in a digital copier or the like employs a technique of reading an image on an original by means of so-called follow shot. In this technique, an image is read while moving an original with respect to a fixed reading section. This technique has the merits that the structure and control of the reading apparatus can be simplified, and that an image can be read at a high speed.
However, the technique has the following problem. When dirt such as dust or a scratch exists in a reading position, the reading section continues to read the dirt during the entire process of moving the original, with the result that a black line appears not only in an read image but also in an output image.
In view of the problem, a technique that dirt on an original glass plate in a reading position is detected and an alarm is then given is disclosed in Japanese Patent Publications (Kokai) Nos. HEI10-56542 and HEI9-83703.
In the technique of the conventional art, however, a countermeasure against dirt which is deposited to a reading position during a reading process is not taken. Therefore, the technique has a problem in that a black line due to dirt deposited to a reading position during a reading process cannot be prevented from appearing in an image.
It is an object of the invention to provide an image reading apparatus in which a black line due to, for example, dirt deposited to a reading position during a reading process can be prevented from appearing in an image.
In order to attain the object, an image reading apparatus of a first feature is an image reading apparatus which reads each of originals that are sequentially transported one by one, the image reading apparatus comprising: a reading unit which reads a transported original; a reference member; detecting means for detecting dirt in the reading unit by reading the reference member; and determining means for, among plural originals read by the reading unit, determining one or more originals on the basis of a detection result of the detecting means, image data which are read from the determined originals being affected by the dirt.
An image reading apparatus of a second feature is an image reading apparatus which reads each of originals that are sequentially transported one by one, the image reading apparatus comprises: a reading unit which reads a transported original in a reading position; a reference member; detecting means for detecting dirt in the reading unit by reading the reference member; and a rereading controller which changes the reading position of the reading unit on the basis of a detection result, of the detecting means, and rereading an original that has been once read.
An image reading method of a third feature is a method of reading an image on originals, and comprises the steps of: reading originals that are sequentially transported by a reading unit; detecting dirt in the reading unit by reading a reference member; determining one or more originals among plural originals based on a detection result of the detection step, image data which are read from the determined originals being affected by the dirt; and rereading the determined original.
An image reading method of a fourth feature is a method of reading images on plural originals, and comprises the steps of: reading originals that are sequentially transported by a reading unit; detecting dirt in the reading unit by reading a reference member; determining one or more originals among plural originals based on a detection result of the detection step, image data which are read from the determined originals being affected by the dirt; and rereading the determined original.
According to these features, it is possible to prevent a black line due to dirt deposited during a process of reading an original, from appearing in an image.
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings which illustrate specific embodiments of the invention.